Locking members for a composite breech block



June 16, 1959 R. AMSLER LOCKING MEMBERS FOR A COMPOSITE BREECH BLOCK Filed May 10, 1956 I 2 Sheets-Sheet 2 w m .v m N8 2 8 z /V l d /I///// v1 0 3. \M J rf/ IV. E. a m 055% BOCKING MEMBERS FOR A COMPOSITE BREECH BLOCK Rudolf Amsler, Neuhausen am Rheinfall, Switzerland,

assignor to Schweizerische Industrie-Gesellschaft, Neuhausen am Rheiufall, Switzerland Application May 10, 1956, Serial No. 584,007 Claims priority, application Switzerland May 13, 1955 (Jlairns. (Cl. 89-180) The present invention has the object of attaining a safe closure of the rear end of the barrel of automatic.

'in the breech body, which locking elements are operatively connected to the striker and to grooves'in the breech housing.

All the mechanisms hitherto in use show some disadvantages. Partlynamely those eflecting the locking purely mechanicallythey involve heavy and complicated weapons which are liable to break-downs and permit a limited firing cadence only. Other mechanisms in which only the inertia of the moveable breech members is used for the instantaneous temporary fixing of the breech members, have proved successful to a certain extent at least for small weapons.

However, they are no longer suflicient as soon as weapons of normal caliber are concerned. New improved mechanisms according to which a rigid mechanical locking is provided which is operated by the inertia action of the moving breech components have brought some improvements in various aspects. However, they still have the disadvantage, that the duration of the locking period, which is dependent on the masses of the breech components taking part in the operation, and on the strength of the interposed springs, is determined for a certain weapon. 7

When for any reason a delay occurs in the priming of a cartridge, the unlocking takes place prematurely in this method. Such unavoidable irregularities as regards the ammunition consequently involve serious disturbances of functioning and, connected therewith, a considerable danger to the gunner.

'The invention has the object of providing a fire arm which ensures a safe functioning independently of irregularities in the ammunition.

The fire arm according to the invention is characterised in that the striker and the striker guide block are braced to one another, and that, between the striker guide block and the breech head, means are provided for the interlocking of these two elements which are put into action during a movement of the striker guide block relative to the breech head and after the initiation of the locking of the breech head by the said locking elements, and which are put out of action during a return movement of the striker relative to these two elements and after the initiation of the unlocking of the breech head which is locked by the said locking elements.

In the accompanying drawings some embodiments of the fire arm according to the invention are diagrammatically illustrated by way of example. With reference thereto the manner of operation according to the invention will be also explained.

ttes Patent 0 ice Fig. 2 shows the same section of the fire arm but immediately after triggering 01f the shot,

Fig. 3 shows the same section of the fire arm, but during the initiation of the release of the locking device,

Fig. 4 shows a section of the fire arm on the line IV-IV of Fig. 3,

Fig. 5 shows a modification of the design of the locking bodies,

Fig. 6 shows a section on the line VIVI of Fig. 5, and

Fig. 7 shows a further modification.

The breech body moveably arranged in the breech housing 1 consists of three members which are slidable relative to one another, namely the breech head 2, the striker 4, which at its forward end is constructed as a percussion pin 3, and of the striker guide block 5. The striker 4 is guided in a longitudinal bore 50 of the striker guide block 5. The breech body as a whole is under the action of the closure spring 6 which abuts on the bottom piece 7 of the weapon and with its other end acts on the head 8 of the striker 4. The head 8 of the striker 4 forms an abutment designed for co-operation with the striker guide block 5. A preloaded spring 9 which abuts at one end on a shoulder, or projection, 10 of the striker 4 and which acts with its other end on the annular face 37 of the striker guide block 5, braces these two parts against one another in such a manner that normally the striker guide block 5 contacts the head 8 of the striker 4 (Fig. 1).

The striker 4 is in turn guided in a bore of the breech head 2 and is freely moveable relative to the latter in the axial direction. On the breech head 2 a bolt 11 is attached which traverses a longitudinal slot 12 in the striker 4. The length of this slot 12 limits the mutual displacement of the two members 2 and 4.

In the breech head 2 two recesses, or transverse bores, 13 (Fig. 4) are machined in alignment with one another in each of which a cylindrical locking element 14, Fig.

. 4, or a ball 42, Fig. 7, is guided moveably. The breech Fig. 1 shows a fire arm in a longitudinal section, name- 1 1y with the breech mechanism cocked,

housing 1 has two locking grooves 15 lying opposite one another in the inner circumferential surface of the forward portion 1a of said breech housing.

The striker guide block 5 carries a pin 16 on which a two-armed pawl 17 is pivotally mounted. The rear arm 18 of the pawl 17 is under the action of the compression spring 19 which abuts on the striker guide block 5. The forward arm 20 of the pawl 17, which has a nose, or a hook shaped portion, 21 at its end, bears accordingly normally on the shoulder 10 of the striker 4 (Fig. 1). The rear end of the breech head 2 is undercut in the range of the pawl 17 to form a hook 22.

When firing, the striker guide block 5 and thereby the whole breech body is released by the action of the sear rod 23 (Fig. 1), so that the compressed closure spring 6, which acts on the head 8 of the striker 4, throws the same forward. The striker carries the striker guide block 5 along with it through theintermediary of the head 8 serving as an abutment.

After a short movement of the striker 4 the wedge face 41 of its end 27 (Fig. 4) comes into engagement with the locking elements 14 and thereby causes the breech head 2 to be carried along in the continued movement. The whole breech body accordingly moves forwardly in the breech housing at high velocity. Thereby the front end of the breech head 2 engages a cartridge 24 (Fig. 2) which is brought into itspath in a usual manner (not shown in detail), and pushes the same into the cartridge chamber 25.

The breech head 2 is brought to an abrupt stop through engagement with the end of the cartridge chamber 25 while the members 4 and 5 continue their movement owing to their inertia. 1n the forward end position of thebreech head 2 its -recesses 13 lie in juxtaposition to the twolocking grooves 15 of the. breech housing. 1. Ac.- cordingly there is nothing more in the way of an outward movement of the cylindrical locking elements 14. Such a displa'cementzis' enforced by the continued movement of the striker 4 Wh'iChiStl'll." acts as before with theiface 41 oftits end 27 onzthe locking elements 14, andi'the said locking elements: are thereby pushed into the locking grooves .of the. breech housing 1. The resistances encountered are overcome by the co-operatingv inertia forces of. theamoving: members 4 and 5. At the moment when the percussion pin 3 finally hits the primer of the cartridge 24 and initiatesthefiring of the shot, the breech head 2 is accordingly already locked to the breech housing 1 by mechanical means,

Between thebreeclrhead. 2 located in its forward end position andxthe. striker 4 stopped by the impact on the breech headand onthe primer, on the one hand, and the striker'guide block 5 continuing its movement owingto with-the corresponding wedge face 30 of the breech head 2', which causes a turning of the pawl 17 in a counterclockwisedire'ction against the force of the spring 19. As. soon=asthe nose 21 has-passed the hook 22 (Fig. 2.), the-.-pawl 17 is turned back in the clockwise direction by theaction of the loaded spring 19 in such a manner that the nose 21 comes to locking engagementwith the hook 22.-of the breech head 2. Preferably wedge faces 31 and 32 are providedonthebreech head 2 and on the end of the arm 20 of the pawl 17, respectively, in such a manner that,: shortly after the nose 21 has passed the hook, they come into engagement with one another and thereby assistthe action of the spring 19 in order to assure always a safe locking action.

In this position the breech head 2, which is locked to the breech housing 1, is accordingly connected to the.

striker guide block 5 by the intermediary of the pawl 17, and the pawl 17 accordingly is subject to the force of the strongly loaded spring 9 and braces the individual membersiof the breech body against one another so as to form aunit. Thereby the end 27 of the striker 4 is pressed with great force against the locking elements 14 which are thus held in the locking position, and the breech body as a wholeis secured in its closingposition.

The. gaspressure which rises in the course of the development of the shot imparts an increasing force on the ation is initiated owing to the movement of the striker 4 relative to the breech head 2. The transmission ratios arising in the transmission of the forces from the breech head 2'" to the striker 4' are determined by the shape of the effective faces 40 and 41 and of the locking elements 14: The resistance opposing the displacement of the striker 4 is determined by the characteristics of the springs 9 and 6. By an appropriate mutual adaptation-of these decisive factors it is attained that the-movement of the striker 4*"relative to the breech body 2 starts at a predetermined gas pressure in the cartridge chamber 25. When thisgas. pressure determining the initiation of'the unlockingis chosen-high enough, any premature unlocking of the body and the" concomitant break-downs of functioning are safely obviated even with irregularities in the ammunition.

In order-toobviateunfavourable'conditions as regards the spring 9, the faces 40 and 41 are advantageously sel'ect'ed in such a manner that the gas forces are reduced to a certain" extent when being transmitted to the striker 4: Ofcourse care has to be taken in this choice that 4'. no self-locking may occur in the transmission of forces, neither. in one nor in the other direction of transmission.

In the movement of the striker 4 relative to the breech head 2, with which already a small return movement of the breech body as a whole is connected, after a certain displacement the control face 34 (Fig. 3) of the shoulder 10 of the striker 4 comes into engagement with a cam 35 provided onthe arm 20 of the pawl 17. Thereby the pawl 17 is turnedin the counterclockwise direction, and thereby'its nose, or book shaped portion, 21 is disengaged frompthehook 22'of the breech head 2. The mutual bracing of the individual members of the breech body is thereby terminated. The return movement of the breech head 2' can then take place completely unhampered, and the gaspressure still prevailing in the barrel throws the whole breech body back. Thereby the case of the cartridge 24 is carried along by the extractor 36 and is accordingly ejected in the usual manner, and moreover the closure spring 6is loaded.

Finally: the'whole breech is restored to its starting position where it is. arrested by'the sear rod 23 in case of single" shots; The weapon is accordingly again ready for firing:

Whenfiring-z aseries. of shots the sear rod 23'is arrestedinrthe triggering oif position. The breech body is accordingly not engaged in its rear position, so that the loaded' closure spring immediately throws the same. forward again.

In themodification illustrated in Figs. 5 and 6, instead oflthe cylindrical locking elements 14, slides 39 provided with cam; faces: 28 are used. The same are moveably arrangedin the recess-13 of the breech head 2, and cooperate with thefaces 33 ofthe grooves 15 provided in the breech housing as well as with the face 26 of the front end27' of the striker 4. The inclined faces 33, 28'and 26 are chosen plane or curved, and by proper selection of these transmission faces the transmission ratio in the transmission of the forces from the breech head 2 to the striker (and vice versa) may be varied in dependence of themutual: position of the two aforesaid components of the breech body, which may be desirable in certain circumstances.

By the. present method itis possible to generate forces for each given type of weapons by the appropriate mutual adaptation. of the various decisive factors (characteristic of the spring9, inertia of the striker guide block 5,- transmission ratio of the forces etc.)'which forces assure with safety the maintenance of the locking'of the breech body up to the moment when the gas pressure in the cartridge ch'amberhas' reached quite a definite value adapted for the weaponand the ammunition in question.

It is. then still always possible to select the gas pressure, at which the unlocking operation isinitiated, in such a mannerth'at on the one-hand a safe locking is ensured independently of delays in the priming, if any, and-on the i other'hand'also a timely unlocking is-assured as required for the' safe functioning of the weapon. Gas forces as required for initiating the unlocking operation may then reach values amounting to a multiple of the force of the closure-spring.

In theweapon described the striker guide block is constructedas a single member. Of course the same could be sub-divided'into two or more individual members moveable relative to one another-and braced resiliently one against the other.

While-I have herein described and illustrated in the accompanying: drawings what may be considered typical through, a striker slidably mounted in said breech head bore and extending rearwardly thereof, means limiting the relative sliding movement between said striker and breech head, a striker guide block slidably mounted in said breech housing rearwardly of said breech head and provided with a longitudinal guide bore therethrough slidably accommodating the rearwardly extending portion of said striker, means limiting the relative sliding movement between said striker guide block and striker, first spring means interposed between said breech housing and said striker urging said striker forwardly in said breech housing, second spring means interposed between said striker guide block and said striker urging said striker forwardly in said striker guide block, interior locking recesses in a forward portion of said breech housing, locking elements movably mounted in said breech head for cooperation with said locking recesses, means on the forward portion of said striker forcing said locking elements into locking engagement with said locking recesses in a forward position of said striker relative to said breech head, cooperating latch means on said breech head and said striker guide block locking said breech head and striker guide block together in said forward position of said striker relative to said breech head, and cooperating cam means on said striker and said latch means releasing said latch means in a rearwardly position of said striker relative to said striker guide block, whereby when the pressure of percussion gases acting on the forward end of said breech head and transmitted by said locking elements to said striker reaches a predetermined value said striker is forced rearwardly to cause release of said latch means through said cam means.

2. The breech mechanism as set forth in claim 1, in which said latch means comprise a hook shaped element on said breech head, pawl means pivotally mounted on said striker guide block and having a hook shaped portion for latching cooperation with said hook shaped element, and yieldable means connected with said pawl means biasing said pawl means towards latching position, said pawl means and said hook shaped element having inclined surfaces thereon in a position to slide upon each other and thereby cause pivotal movement of said pawl means against the action of said yieldable means when said striker guide block is moved towards said breech head for latching engagement therewith.

3. The breech mechanism as set forth in claim 2, in which said cam means include a cam on said pawl means, and a projection on said striker for engagement with said cam.

4. The breech mechanism as set forth in claim 1, in which said locking elements and said recesses have cooperating inclined surfaces facilitating the locking and unlocking movements.

5. The breech mechanism as set forth in claim 1, in which said locking elements comprise balls movably mounted in a transverse bore through said breech head, and said means on the forward portion of said striker comprise inclined surfaces thereon for cooperation with said balls.

References Cited in the file of this patent UNITED STATES PATENTS 2,476,232 Williams July 12, 1949 2,775,166 Ianson Dec. 25, 1956 FOREIGN PATENTS 142,974 Austria Oct. 10, 1935 1,046,084 France July 8, 1953 416,218 Italy Nov. 20, 1946 

